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DesignPatternsintermediate

Strategy — Runtime strategy swap

📖 Usage Example
let strategy = (a, b) => a - b;
function sort(arr) { return [...arr].sort(strategy); }
// change strategy at runtime:
strategy = (a, b) => b - a;

Swap the strategy variable at runtime to change behavior without modifying calling code.

Strategy Pattern — Changing Strategy at Runtime

The strategy can be changed after the Sorter is created.

Challenge: Implement a Sorter class with a setStrategy(strategy) method to change the sorting algorithm at runtime.

Example:

const sorter = new Sorter()
sorter.setStrategy((a, b) => a - b)
sorter.sort([3, 1, 2]) // [1, 2, 3]
sorter.setStrategy((a, b) => b - a)
sorter.sort([3, 1, 2]) // [3, 2, 1]
💡 Hints (4)
  • • Initialize strategy to null or undefined
  • • Add setStrategy method
  • • Update this.strategy in setStrategy
  • • Use current strategy in sort